There is disclosed a technology for performing voice recognition by using a dictionary that registers therein acoustic feature values of words to be matched with input voices.
Patent Literature 1 discloses a technology regarding the voice recognition. In the technology disclosed in Patent Literature 1, in the dictionary, there are registered acoustic feature values of words to be recognized and acoustic feature values of words (unnecessary words) other than the words to be recognized. Then, the unnecessary words are removed from a plurality of the words recognized by the voice recognition.